Embankment dam with interior membrane



June 15, 1965 E. RE-rrls EMBANKMENT DAM4 WITH INTERIOR MEMBRANE Filed May 9, 1962 3,188,814 EMBAENT DAM WITH INTERIOR MEMBRANE Erik Rettig, Belvedere, Calif., assignor to The Dow Chemical Company, Midiand, Mich., a corporation of Delaware Filed May 9, 1962, Ser. No. 193,373 3 Claims. (Ci. oli- 31) This invention relates to embankment dams and more particularly to a dam construction having a plastic membrane water barrier.

In the construction of embankment dams, it is known to utilize a central or sloping core of low permeability, or a membrane water barrier. Reference may be made to U.S. Patent 1,997,132, issued April 9, 1935, as an illustration of such type dam construction. Such prior art constructions generally utilize a sloping membrane at or near the water side of the structure, and the use of concrete, steel, wood, or asphalt, or a combination of these as membrane material.

The darn construction of the subject invention represents an improvement in the art and will be found to provide substantial savings in design and construction costs, in comparison with dams of conventional design. ln addition, a dam incorporating the principles of the invention will provide a water barrier effective to a degree generally not attainable by conventional design, since the area of the plastic membrane will be practically 100% effective and is substantially immune to normally deteriorating factors.

A main object of this invention is to provide an improvement in the construction of embankment dams.

A more specific object of the invention is to provide an improvement in dam construction whereby substantial savings in design and construction costs are realized.

Another object is to provide a plastic membrane which is substantially immune to normally deteriorating forces.

Still another object is to provide a film like plasticelastic membrane which can be solvent welded on the dam situs and which after being installed, will adjust without rupture to dam settlement.

These and further objects and features of the invention will become more apparent from the following description and accompanying drawing wherein:

FiG. 1 is a section view of a rock-fill dam embodying the principles of the invention; and

FIG. 2 is an enlarged section View of a portion of the dam shown in FIG. 1.

Referring now to the drawing, the numeral identifies a dam of the rock-till type having embankments 12 and 14, each of which may be arranged with a slope to satisfy the stability of the embankment material without need of supporting a less stable conventional earth core. A slope having a ratio of 1 to 1.35 may be satisfactory in many cases. The dam 10 is designed to maintain a given y body of water 16 on one side.

A water barrier, illustrative of an embodiment of the invention, includes a membrane in the form of a lm or a sheet of plastic-elastic material 18, which is constructed vertical or within a range of about 2O degrees of vertical and which extends in an unbroken manner along the length of the dam, and to substantially the height of the dam. The sheet is located in a cushion and transition VAited States Patent() "ice duced by The Dow Chemical Company and known as Saraloy 400. This material is composed of saran (vinylidene chloride copolymer) polymer, carbon black, and suitable plasticizers and stabilizers. The composition of the material is from about to about 88 weight percent interpolymerized vinylidene chloride and from about 20 to about 12 weight percent interpolymerized acrylonitrile; from about 20 to about 80 parts by weight for each 100 parts by weight of said copolymers of a non-volatile plasticizer for said copolymer; and from about 30 to about parts by weight of a soft reinforcing carbon per 100 parts by weight of said copolymer. The non-volatile plasticizer may be dibutyl phthalate, or a mixture consisting of about 55 percent by weight of ethoxy diglycol phthalate, about 36 percent by weight of n-butyl benzyl phthalate, and about 9 percent by weight of dibutyl phthalate. Another suitable plasticizer mixture may contain about 40 percent by weight of n-butyl phthalate and abou-t `60 percent by weight of dicarbitol phthalate. The composition is thoroughly blended in a ribbon blender, or similar device, and thereafter extruded into a continuous sheet of about '1/16 inch thick.

Said plastic material i.e., Saraloy 400 exhibits a combination of desirable characteritsics not found in any other available water-proofing membrane material. For example, it is not materially affected by water immersion, ASTM 2li-hour absorption being less than 0.4%. The perm rating of moisture vapor transmission was established as 0.104 perms, while water penetrating rate was determined as 0.336 grams/24 hours/ 100 sq. in. under 5.9 to 6.1 inches of water at 100 F. It does not support the growth of, nor is it affected by mildew. An important characteristic of said material is that it can easily be joined to itself at the dam situs through the use of methyl ethyl ketone ysolvent to form an elastic waterproof joint having shear strengths greater than the base material itself. By eliminating the need for adhesives in the joining process, the failure of the joint due to the eventual failure of the adhesive over a given period of time has been correspondingly eliminated. The service temperature range for the material extends from 20 F. to +175 F.

It is believed that the foregoing outline of the characteristics of Saraloy 400, will provide a good understanding of its suitability as a membrane in a dam construction made in accordance with the principles of the invention. Other plastic film materials having the similar characteristics of being water impermeable, having an elastic quality so as not to rupture on dam settlement and being easily self-weldable in the eld without the need for the use of adhesives or the like can, of course, be used if desired. For example, ethylene-copolymers of low crystallinity, i.e., less than about 10 percent as measured by X-ray diffraction and more especially such copolymers as are characterized by high resilience, low modulus, high elongation and high reversible elastic response can also be employed as a membrane. Such copolymers may be prepared as taught in Italian Patent No. 554,803. These high molecular weight copolymers of ethylene and other non-aromatic, terminally-unsaturated monooletns of from 3 to 4 carbon atoms (such as l-butene and especially propylene), substantial-ly free of hornopolymers of the constituent oleiins and having elastomeric properties, can be obtained by interpolymerization of a mixture of ethylene aud said monooletins with certain catalysts such as organometallic compounds like triaikylaluminum and transition metal compounds like halides or Oxy-halides of vanadium or titanium. Copoiymers of ethylene with vinyl acetate or with ethylacrylate as described in U.S. Patent 2,200,429 specifically can be useful in membrane construction according to this invention.

The foregoing description has been given in detail without thought of limitation since the inventive principles involved are capable of assuming other forms without departingfrom the spirit of the invention or the scope of the following claims. l

What is claimed is: Y

1. An embankment dam, a foundation coextensive therewith, an impervious water barrier within said dam consisting of a continuousy pliant plastic-elastic sheet across the extent of said darn, a cushion and transition zone made up of tine owable particulate material contacting and completely covering both faces ofV said sheet thereby providing a cushion and transition zone shielding said sheet, said sheet being located within said darn and sealed to and coextensive with the-length of saidfounda-V tion and extending substantially to the top of said dam,

said sheet being substantiallyvwater impermeable, of high resilence and joinable to similar vplastic-elastic sheets whereby a continuous sheet extendingoverV the entire area of the dam in an unbroken manner can be easily formed at the situs of the dam. v

2. The embankment dam construction of claim'l wherein said cushionand transition zone is composed principally ofv sand. Y f Y o 3; An embankmentv darn, a foundation coextensive therewith, an impervious water barrier within said darn consisting of a continuous pliant plasticlelastic sheet across thek extent of said dam, a cushion and transition zone made up of tine owable particulate material contacting and completelycovering bothfaees of said sheet thereby providing a cushion and v transition zone shielding said sheet, said sheet being located within said darn and sealed to and coextensive with the length of's'aid foundation and extending substantially to the top of said dam, said Vsheet,

being substantially water impermeable, of high resilience and joinable .to similar plastic-elastic sheets by the application of solvent whereby a continuous sheet extending over the entire area ofV the'dam in an unbroken manner can be easily formed at the situs of the darn, `said sheet being aiiixed in liquid-tight manner to a foundation positioned along its lower edge.

References Cited by the Examiner VUNITED STATES PATENTS 922,207 "5/09 "strauss 61-31 1,997,132 4/35 Cenone 61-31 2,996,843.VY s/61 Mack' j 50-43 Y 'FOREIGN PATENTS 189,572 4/57 Austria.'y

715,126' 9/54 Great Britainp`- 1,000,293 V1/57 Germany.

EARL-J. WITMER, Primaryv Examiner. JACOB L. NACKENOFE, lllrarmz'ner.l 

1. AN EMBANKMENT DAM, A FOUNDATION COEXTENSIVE THEREWITH, AN IMPERVIOUS WATER BARRIER WITHIN SAID DAM CONSISTING OF A CONTINUOUS PLIANT PLASTIC-ELASTIC SHEET ACROSS THE EXTENT OF SAID DAM, A CUSHION AND TRANSITION ZONE MADE UP OF FINE FLOWABLE PARTICULATE MATERIAL CONTACTING AND COMPLETELY COVERING BOTH FACES OF SAID SHEET THEREBY PROVIDING A CUSHION AND TRANSITION ZONE SHIELDING SAID SHEET, SAID SHEET BEING LOCATED WITHIN SAID DAM AND SEALED TO AND COEXTENSIVE WITH THE LENGTH OF SAID FOUNDATION AND EXTENDING SUBSTANTIALLY TO THE TOP OF SAID DAM, SAID SHEET BEING SUBSTANTIALLY WATER IMPERMEABLE, OF HIGH RESILENCE AND JOINABLE TO SIMILAR PLASTIC-ELASTIC SHEETS WHEREBY A CONTINUOUS SHEET EXTENDING OVER THE ENTIRE AREA OF THE DAM IN AN UNBROKEN MANNER CAN BE EASILY FORMED AT THE SITUS OF THE DAM. 